Coaxial cables are a specific type of communications cable that may be used to carry information signals such as television or data signals. Coaxial cables are widely used in cable television networks and/or to provide broadband Internet connectivity. FIGS. 1A and 1B are, respectively, a schematic transverse cross-sectional view and a schematic longitudinal cross-sectional view of a conventional coaxial cable 10 (FIG. 1B is taken along the cross section B-B shown in FIG. 1A). As shown in FIGS. 1A and 1B, the coaxial cable 10 has a central conductor 12 that is surrounded by a dielectric 14. A tape 16 is preferentially bonded to the dielectric 14. The central conductor 12, dielectric 14 and tape 16 comprise the core 18 of the cable. Electrical shielding wires 20 and, optionally, electrical shielding tape(s) 22 surround the cable core 18. Finally, a cable jacket 24 surrounds the electrical shielding wires 20 and electrical shielding tape(s) 22. As shown in FIG. 1B, the dielectric 14, tape 16, electrical shielding wires 20, electrical shielding tape 22 and cable jacket 24 may be cut, and the electrical shielding wires 20 may be folded back, in order to prepare the coaxial cable 10 for attachment to certain types of coaxial connectors.
Coaxial connectors are a known type of connector that may be used to connect two coaxial cables 10 or to connect a coaxial cable 10 to a device (e.g., a television, a cable modem, etc.) having a coaxial cable interface. Coaxial “F” connectors are one specific type of coaxial connector that is used to terminate a coaxial cable with a male coaxial connector.
Standards promulgated by the Society of Cable Telecommunications Engineers (“SCTE”) and, more specifically, ANSI/SCTE 99 2004, specify an axial tension pull-off or retention force that a coaxial “F” connector must impart on the coaxial cable onto which it is installed. Specification of this minimum retention force ensures that the connector will resist pulling forces that may be applied to the cable during normal use such that the cable will not readily separate from the coaxial “F” connector. Other ANSI/SCTE standards specify moisture migration parameters, electrical parameters, other mechanical parameters and environmental requirements. Relevant standards documents include the ANSI/SCTE 123 2006, 99 2004, 60, 2004 and 98 2004 standards.
A number of different types of coaxial “F” connector designs are known in the art, including, but not limited to, crimped on connectors, swaged on connectors and connectors which secure the cable into the connector with compression style cable retention elements. With the crimped connector designs, typically a hexagonal-shaped tool is used to crimp a sleeve of the connector onto the coaxial cable that is to be terminated into the connector. With the swaged connector designs, the sleeve of the connector is swaged circumferentially inward so as to reduce its inside diameter in order to exert the required retention force on the coaxial cable.
Several different coaxial “F” connector designs are currently known in the art that have compression style cable retention elements. FIGS. 2-4 depict a connector 100 according to a first of these designs. As shown in FIGS. 2-4, the connector 100 includes a tubular connector body 110, a compression sleeve 130, a contact post 150 and an internally threaded nut 170. A coaxial cable 10 (not shown in FIGS. 2-4) is inserted axially into the inside diameter of the tubular connector body 110 and the compression sleeve 130 (when the connector is oriented as shown in FIGS. 2-4, the coaxial cable 10 is inserted into the right side of the connector 130). The core 18 of the coaxial cable 10 inserts axially into an inside diameter of the contact post 150, while the electrical shielding wires/tape 20/22 and the cable jacket 24 circumferentially surround the outer surface of contact post 150. The outside surface of the contact post 150 may include one or more serrations, teeth, lips or other structures 152. Once the cable 10 is inserted into the connector 100 as described above, a compression tool (not shown in FIGS. 2-4) is used to axially insert the compression sleeve 130 further into the tubular connector body 110 into its seated position in which the compression sleeve 130 locks the cable 10 in place within the connector 100. The compression sleeve 130 directly decreases the radial gap spacing between the connector body 110 and the contact post 150 so as to radially impart a 360-degree circumferential compression force on the electrical shielding wires/tape 20/22 and the cable jacket 24 that circumferentially surround the outer surface of contact post 150. This compression, in conjunction with the serrations, teeth or the like 152 on the outside surface of the contact post 150, result in an engaging or retention force that is applied to the coaxial cable 10 that meets SCTE requirements for connector pull-off as well as additional electrical, mechanical and environmental requirements. In addition, this engaging/retention force may also contribute toward a positive moisture seal at the cable-connector interface. An example of a prior art connector having the design of connector 100 is provided in U.S. Pat. No. 7,192,308.
FIG. 5 illustrates a second conventional compression style back-fitting coaxial “F” connector 200. As shown in FIG. 5, the connector 200 includes a tubular connector body 210, a compression sleeve 230, a contact post 250 and an internally threaded nut 270. The connector body 210 of connector 200 is shorter than is the connector body 110 of connector 100. Moreover, the compression sleeve 230 fits over the outside surface of the connector body 210. The compression sleeve 230 includes an annular internal element 242 that is designed to fit between the contact post 250 and the inside surface of the connector body 210 when the compression sleeve 230 is inserted axially into its seated (i.e., fully engaged or activated) position within the connector body 210. As a result, the annular internal element 242 may directly engage the shielding wires 22 and/or jacket 24 of a cable 10 that is inserted into and over the contact post 250 in the same manner that the main body of compression sleeve 130 of connector 100 engages a coaxial cable as is described above with reference to FIGS. 2-4. As such, similar to the connector 100 discussed above with respect to FIGS. 2-4, this second conventional connector 200 uses a sleeve 230 to contact and engage annular internal element 242 such that annular internal element 242 directly imparts a 360-degree circumferential compression on the contact post 250. This 360-degree circumferential compression imparts an engaging or retention force that meets SCTE requirements for connector pull-off and provides a moisture seal. An example of a prior art connector having the design of connector 200 is provided in U.S. Pat. No. 7,182,639.
FIGS. 6 and 7 illustrate a third conventional coaxial “F” connector 300. As shown in FIGS. 6 and 7, the connector 300 includes a tubular connector body 310, a compression sleeve 330, a contact post 350 and an internally threaded nut 370. The connector 300 further includes a reinforcing shield 380 that fits over a portion of the connector body 300. As shown in FIG. 7, the compression sleeve 330 fits over the outside diameter of the connector body 310. The outside radius of the connector body 310 may be slightly larger than the inside radius of a portion of the compression sleeve 330. A compression tool is used to force the compression sleeve 330 over the connector body 310, and in the process the connector body 310 deforms inwardly to assert a compression/retention force on the jacket 24 and electrical shielding wires/tape 20/22 of a coaxial cable 10 that is inserted into and over the contact post 350 in the same manner described above with reference to connector 100 of FIGS. 2-4. In this manner, the compression sleeve 330 is used to indirectly radially decrease the gap spacing between the underlying connector body 310 and the contact post 350. In particular, the compression sleeve 330 imparts a 360-degree circumferential compression on the tubular connector body 310 which, in turn, deforms to impart a circumferential compression on the outside components of the cable 10 and on the contact post 350. The resulting engaging or retention force may meet SCTE requirements for connector pull-off, and may also contribute to providing a positive moisture sealing at the cable-connector interface. An example of the prior art F-connector design of FIGS. 6-7 is provided in U.S. Pat. No. 7,255,598.